diff --git a/include/libs/catalog/catalog.h b/include/libs/catalog/catalog.h
index de37807cf6..395116b3bc 100644
--- a/include/libs/catalog/catalog.h
+++ b/include/libs/catalog/catalog.h
@@ -20,6 +20,96 @@
 extern "C" {
 #endif
 
+#include "os.h"
+#include "thash.h"
+#include "tarray.h"
+#include "taosdef.h"
+#include "transport.h"
+
+struct SCatalog;
+
+typedef struct SMetaReq {
+  char    clusterId[TSDB_CLUSTER_ID_LEN];
+  SArray *pTableName;     // table full name
+  SArray *pVgroup;        // vgroup id
+  SArray *pUdf;           // udf name
+  bool    qNodeEpset;     // valid qnode
+} SMetaReq;
+
+typedef struct SMetaData {
+  SArray    *pTableMeta;  // tableMeta
+  SArray    *pVgroupInfo; // vgroupInfo list
+  SArray    *pUdfList;    // udf info list
+  SEpSet    *pEpSet;      // qnode epset list
+} SMetaData;
+
+typedef struct STableComInfo {
+  uint8_t numOfTags;      // the number of tags in schema
+  uint8_t precision;      // the number of precision
+  int16_t numOfColumns;   // the number of columns
+  int32_t rowSize;        // row size of the schema
+} STableComInfo;
+
+/*
+ * ASSERT(sizeof(SCTableMeta) == 24)
+ * ASSERT(tableType == TSDB_CHILD_TABLE)
+ * The cached child table meta info. For each child table, 24 bytes are required to keep the essential table info.
+ */
+typedef struct SCTableMeta {
+  int32_t  vgId:24;
+  int8_t   tableType;
+  uint32_t tid;
+  uint64_t uid;
+  uint64_t suid;
+} SCTableMeta;
+
+typedef struct SSchema {
+  uint8_t type;
+  char    name[TSDB_COL_NAME_LEN];
+  int16_t colId;
+  int16_t bytes;
+} SSchema;
+
+/*
+ * Note that the first 24 bytes of STableMeta are identical to SCTableMeta, it is safe to cast a STableMeta to be a SCTableMeta.
+ */
+typedef struct STableMeta {
+  int32_t        vgId:24;
+  int8_t         tableType;
+  uint32_t       tid;
+  uint64_t       uid;
+  uint64_t       suid;
+  // if the table is TSDB_CHILD_TABLE, the following information is acquired from the corresponding super table meta info
+  int16_t        sversion;
+  int16_t        tversion;
+  STableComInfo  tableInfo;
+  SSchema        schema[];
+} STableMeta;
+
+/**
+ * Catalog service object, which is utilized to hold tableMeta (meta/vgroupInfo/udfInfo) at the client-side.
+ * There is ONLY one SCatalog object for one process space, and this function returns a singleton.
+ * @param pMgmtEps
+ * @return
+ */
+struct SCatalog* getCatalogHandle(const SEpSet* pMgmtEps);
+
+/**
+ * Get the required meta data from mnode.
+ * Note that this is a synchronized API and is also thread-safety.
+ * @param pCatalog
+ * @param pMetaReq
+ * @param pMetaData
+ * @return
+ */
+int32_t catalogGetMetaData(struct SCatalog* pCatalog, const SMetaReq* pMetaReq, SMetaData* pMetaData);
+
+/**
+ * Destroy catalog service handle
+ * @param pCatalog
+ */
+void destroyCatalog(struct SCatalog* pCatalog);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/libs/catalog/inc/catalogInt.h b/source/libs/catalog/inc/catalogInt.h
index f6f8a61faf..5b50bbff4c 100644
--- a/source/libs/catalog/inc/catalogInt.h
+++ b/source/libs/catalog/inc/catalogInt.h
@@ -20,6 +20,13 @@
 extern "C" {
 #endif
 
+#include "catalog.h"
+
+typedef struct SCatalog {
+  void       *pMsgSender;   // used to send messsage to mnode to fetch necessary metadata
+  SHashObj   *pData;        // items cached for each cluster, the hash key is the cluster-id, returned by mgmt node
+} SCatalog;
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/libs/catalog/src/catalog.c b/source/libs/catalog/src/catalog.c
index 6dea4a4e57..c553e1bfbf 100644
--- a/source/libs/catalog/src/catalog.c
+++ b/source/libs/catalog/src/catalog.c
@@ -11,4 +11,6 @@
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
\ No newline at end of file
+ */
+
+#include "catalogInt.h"